Conversion of plastic waste into extrudable pellets

Abstract

The invention relates to an apparatus for the conversion of plastic waste into usable material, in which a number of rotating knives are arranged at the bottom of a cylindrical space receiving the plastic waste, and in which by deflecting means arranged along the periphery of said space, the plastic waste, while being cut and circulated by the rotating knives, is directed back into the path of said rotating knives.

I claim: 
     
       1. In an apparatus for the conversion of plastic waste into usable material, means including an upright wall forming a cylindrical working space, at least one rotatable knife arranged at the bottom of said space coaxial therewith, and counter action tools arranged along the wall at the bottom of said space, facing said knife, means above said knife at the top of said space for charging said space with plastic waste; and elongted means attached to said wall at a predetermined height substantially above, and separated from said counter action tools, and projecting from said wall at a distance small against the radius of said wall; said elongated means extending at said height circumferentially and in the direction of its elongation, at least along a portion of the periphery of said wall; and while said waste is being cut and circulated by said knife and thereby rising along the wall, reflecting said rising waste at said height back toward the path of said knife. 
     
     
       2. Apparatus according to claim 1, wherein said elongated means are arranged to point substantually downward into a direction forming an angle with the vertical. 
     
     
       3. Apparatus according to claim 1, wherein said elongated means have a guiding surface projecting perpendicularly from the circumference into the space, for a distance which is small against the radius of said space, extending at the same time along the circumference for a distance of the order of one eighth of said circumference in a downward direction. 
     
     
       4. Apparatus according to claim 1, wherein said counter action tools consist of a number of equal, substantially planary panels arranged in a continuous circle, one angularly joined to another along the bottom of the wall and along its circumference the planes of said panels extending substantially parallel to the axis of the space; each planary panel extending along said circumference as well as upward and downward to the bottom from a center point facing said knife while rotating; each panel thus forming a planary surface perpendicular to the radial extension of the knife, and also forming an acute angle with the circumference to deflect the plastic waste driven by the knife against it, back into the path of said knife. 
     
     
       5. Apparatus for the conversion of plastic waste into a flowing granulate, comprising a cylindrical container with inlet and outlet; and in its lower portion arranged around the axis of the container, a beating comminution tool with radial arms circulating to comminute, heat and agglomerate the waste, counter action tools being arranged along the wall of the container, facing said beating comminution tool; and consisting of a number of plane elements with sides angularly joined to each other, forming at least one sheet-like structure with a polygon-like cross section; each element extending along the circumference of the wall as well as upward and downward from a center point, thus forming a plane surface perpendicular to the radial arms when passing the center point, and also forming an acute angle with the circumference so that the plastic waste driven by the circulating tool against a plane element will be guided back into the path of said circulating tool. 
     
     
       6. Apparatus according to claim 5, wherein said sheet-like structure -- looked at cross-sectionally -- includes a number of planary surfaces, having central sections carrying polygontype knife portions projecting from the structure into the direction of the container axis. 
     
     
       7. In an apparatus for the conversion of plastic waste into a flowing granulate, a substantially cylindrical upright container having inlet and outlet, and in its bottom space coaxial with said container, a beating comminution tool arranged to circulate for the comminution, heating and agglomeration of the waste; and counter action tools arranged along the wall of said container within the operating range of the beating comminution tool thereby impeding the movement of said waste along the periphery of the bottom of the wall while permitting its rise upward along the wall, and at least one elongated element attached to the inside of the container wall in a position at a predetermined height substantially above and separate from said counter action tools; said elongated element having a surface facing downward and extending peripherally along a predetermined portion of said wall, and projecting from said wall to the inside of said container for a distance which is small against the radius of said wall, thereby preventing the waste from rising upward along the wall beyond said predetermined height. 
     
     
       8. Apparatus according to claim 7, wherein said elongated element is arranged perpendicular to the inner wall of said container, downwardly inclined in the direction of rotation of said beating comminution tool at an angle of about 35° to 45° with respect to the axis of the container. 
     
     
       9. Apparatus according to claim 7, wherein said elongated element comprises a helicoidally wound rod, in the form of an L-profile, having one surface attached to the wall, and another surface forming said downward facing surface. 
     
     
       10. Apparauts according to claim 7, wherein the lower end of said downward facing surface is arranged at a distance of about 10 to 30 mm above the position of said beating comminution tool. 
     
     
       11. Apparatus according to claim 7, wherein the projection onto a horizontal plane, of the length of said surface amounts to about a quarter of the circumference of the container. 
     
     
       12. Apparatus according to claim 7, wherein said downward facing surface has an end portion gradually increasing in width, from a point where it originates at the inner wall of the container said end portion being disposed in a region of said surface, which -- seen in the direction of rotation of the beating comminution tool -- is nearest.